Hint for cryptsetup and encrypted USB sticks

After a while of wondering, why I couldn't access my encrypted usb stick, I found a simple solution:

modprobe cryptoloop
modprobe dm_crypt

I thought, nowadays, all such things work nearly automatically - even gnome asks me when inserting the stick for the password - but it fails twice - for one thing, it doesn't work unless the packages cryptsetup is installed (UBuntu/Debian) - and I really wonder why it asks me for a passwword if the command it wants to use it with isn't even available - the second are these modules.

Without them, I got(now, not in gnome, on the command line):

Enter LUKS passphrase:
Failed to setup dm-crypt key mapping.
Check kernel for support for the aes-cbc-essiv:sha256 cipher spec and verify that /dev/sdb2 contains at least 133 sectors.
Failed to read from key storage
Command failed: No key available with this passphrase.

Reading only the last part can make you think you forgot the pass - sometimes, Linux error messages get harder to read...